Semiconductor devices are used in a variety of electronic applications, such as personal computers, cell phones, digital cameras, and other electronic equipment, as examples. Semiconductor devices are typically fabricated by sequentially depositing insulating or dielectric layers, conductive layers, and semiconductive layers of material over a semiconductor substrate, and patterning the various material layers using lithography to form circuit components and elements thereon, forming an integrated circuit.
The upper material layers of semiconductor devices typically comprise metallization layers that are used to interconnect various electrical devices and elements formed on an integrated circuit (IC). The metallization layers are typically formed in a back end of line (BEOL) of a semiconductor manufacturing process, for example. However, the lower layers of semiconductor devices do not typically contain metal, because some metals may contaminate semiconductive materials in some applications. The fabrication of lower levels of semiconductor devices formed before metallization layers are formed is often referred to as a front end of line (FEOL) of a semiconductor manufacturing process, for example.
Structures that are referred to in the art as “sinker contacts” are often used to make electrical connection in the FEOL to devices formed on a semiconductor workpiece or substrate comprising a conductive buried layer, for example. Sinker contacts are typically formed by implanting or diffusing a dopant into a substrate, and annealing or heating the substrate to drive the dopant deeper into the substrate. The dopant causes the semiconductive material to be more conductive; thus, sinker contacts may be used to make electrical connection to conductive buried layers in the substrate.
Trench contacts are typically used to make electrical contact to a substrate beneath the buried layer. However, trench contacts and sinker contacts comprise differently doped semiconductive materials, which may cause problems during the trench etch due to differently doped silicon areas. If trench contacts are placed close to sinker contacts, crystalline defects such as slip-lines may occur, which are cracks in the crystalline structure of the silicon that may cause electrical problems or device defects and failures. Therefore, trench contacts and sinker contacts must be spaced apart from one another by a relatively large distance, e.g., by about 10 to 15 μm or greater, in order to avoid etch problems, slip-lines, and crystal defects. However, spacing trench contacts and sinker contacts by such large distances requires a large amount of surface area on a chip and limits the amount a semiconductor device may be reduced in size.
Thus, what are needed in the art are improved and more area-efficient sinker contact structures for semiconductor devices and methods of manufacture thereof.